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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.net.dhcp;
     18 
     19 import java.net.InetAddress;
     20 import java.net.Inet4Address;
     21 import java.nio.ByteBuffer;
     22 import java.util.List;
     23 
     24 /**
     25  * This class implements the DHCP-OFFER packet.
     26  */
     27 class DhcpOfferPacket extends DhcpPacket {
     28     /**
     29      * The IP address of the server which sent this packet.
     30      */
     31     private final InetAddress mSrcIp;
     32 
     33     /**
     34      * Generates a OFFER packet with the specified parameters.
     35      */
     36     DhcpOfferPacket(int transId, boolean broadcast, InetAddress serverAddress,
     37                     InetAddress clientIp, byte[] clientMac) {
     38         super(transId, Inet4Address.ANY, clientIp, Inet4Address.ANY,
     39             Inet4Address.ANY, clientMac, broadcast);
     40         mSrcIp = serverAddress;
     41     }
     42 
     43     public String toString() {
     44         String s = super.toString();
     45         String dnsServers = ", DNS servers: ";
     46 
     47         if (mDnsServers != null) {
     48             for (InetAddress dnsServer: mDnsServers) {
     49                 dnsServers += dnsServer + " ";
     50             }
     51         }
     52 
     53         return s + " OFFER, ip " + mYourIp + ", mask " + mSubnetMask +
     54                 dnsServers + ", gateway " + mGateway +
     55                 " lease time " + mLeaseTime + ", domain " + mDomainName;
     56     }
     57 
     58     /**
     59      * Fills in a packet with the specified OFFER attributes.
     60      */
     61     public ByteBuffer buildPacket(int encap, short destUdp, short srcUdp) {
     62         ByteBuffer result = ByteBuffer.allocate(MAX_LENGTH);
     63         InetAddress destIp = mBroadcast ? Inet4Address.ALL : mYourIp;
     64         InetAddress srcIp = mBroadcast ? Inet4Address.ANY : mSrcIp;
     65 
     66         fillInPacket(encap, destIp, srcIp, destUdp, srcUdp, result,
     67             DHCP_BOOTREPLY, mBroadcast);
     68         result.flip();
     69         return result;
     70     }
     71 
     72     /**
     73      * Adds the optional parameters to the server-generated OFFER packet.
     74      */
     75     void finishPacket(ByteBuffer buffer) {
     76         addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_OFFER);
     77         addTlv(buffer, DHCP_SERVER_IDENTIFIER, mServerIdentifier);
     78         addTlv(buffer, DHCP_LEASE_TIME, mLeaseTime);
     79 
     80         // the client should renew at 1/2 the lease-expiry interval
     81         if (mLeaseTime != null) {
     82             addTlv(buffer, DHCP_RENEWAL_TIME,
     83                 Integer.valueOf(mLeaseTime.intValue() / 2));
     84         }
     85 
     86         addTlv(buffer, DHCP_SUBNET_MASK, mSubnetMask);
     87         addTlv(buffer, DHCP_ROUTER, mGateway);
     88         addTlv(buffer, DHCP_DOMAIN_NAME, mDomainName);
     89         addTlv(buffer, DHCP_BROADCAST_ADDRESS, mBroadcastAddress);
     90         addTlv(buffer, DHCP_DNS_SERVER, mDnsServers);
     91         addTlvEnd(buffer);
     92     }
     93 
     94     /**
     95      * Notifies the state machine of the OFFER packet parameters.
     96      */
     97     public void doNextOp(DhcpStateMachine machine) {
     98         machine.onOfferReceived(mBroadcast, mTransId, mClientMac, mYourIp,
     99             mServerIdentifier);
    100     }
    101 }
    102